|
Submitted to: Encyclopedia of Soil Science
Publication Type: Book / Chapter Publication Acceptance Date: 2/14/2001 Publication Date: N/A Citation: N/A Interpretive Summary: The interrelation between heat and water flow in soil is complex. These interactions are often neglected to simplify analysis of thermal and/or moisture regimes of soil. However, many situations and processes require that soil heat and water flow be analyzed simultaneously. Soil freezing during cold-season processes, and water vapor movement in conjunction with soil surface evaporation are two examples where thermal and moisture processes are tightly linked and require simultaneous evaluation. These and other less obvious interrelations between soil heat and water are discussed. Scientists and hydrologic modelers can use this information when performing analyses or formulating computer models to properly address these processes and to when the problem can be simplified without losing accuracy. Technical Abstract: The interrelation between heat and water flow in soil is complex. Temperature gradients can induce vapor and liquid water transfer within the soil; in turn, water movement carries heat with it, thus altering the thermal regime of soil. These interactions are often neglected to simplify analysis of thermal and/or moisture regimes of soil. However, many situations and processes require that soil heat and water flow be analyzed simultaneously. Soil freezing during cold-season processes, and water vapor movement in conjunction with soil surface evaporation are two examples where thermal and moisture processes are tightly linked and require simultaneous evaluation. These and other less obvious interrelations between soil heat and water are discussed. Interrelation between water and heat flow within the soil can influence the soil temperature regime. This influence is most pronounced in the case of soil freezing and thawing, and water vapor movement during surface evaporation. With the exception of rapid infiltration of water, heat carried by liquid water flow can usually be ignored. Thermally-induced liquid water flow is usually insignificant. From a practical standpoint, although water vapor movement influences evaporation from the soil and in turn affects water availability for plant growth, ignoring this process usually provides evaporation estimates within 10% of actual values. Soil freezing, however, can significantly influence infiltration and runoff, causing severe flooding from relatively mild rainfall or snowmelt events. |
